Magnetic key cards such as described in Sedley U.S. Pat. No. 4,077,242 “Metal Magnetic Key” require a substantial amount of magnetic energy to encode discrete magnetic areas in specific locations to operate card locks that utilize magnetic pin tumblers to form the code of the lock, for example, the “Magnetic Key Operated Door Lock” as described in Sedley U.S. Pat. No. 4,133,194. The method that has been utilized for many years is an electronic device such as described in Sedley U.S. Pat. No. 4,128,851 “Hand Held Magnetic Encoder.”
Developments of new permanent magnetic materials in recent years, such as Neodymium which has very strong magnetic properties, have been found to be of sufficient strength so that by forming a magnet of the proper size and simply touching it to the said magnetic key creates a magnetic area of sufficient strength to actuate the magnetic pin tumblers in a lock. As the permanent magnet has North and South opposing poles, the polarity of the magnetic area created on the key can be either North or South, depending on which end of the magnet was used to create the magnetized area on the key.
The advantage of using a device that can encode magnetic keys in this manner is that electric power does not have to be utilized for the encoding device, and the parts which often fail in those devices such as the electric switches that turn on the device or change its polarity are no longer a source of faulty encoding. When the electric encoding device is battery operated there has always been the problem that when the batteries become weak so does the resulting magnetic area on the key, and the person doing the encoding may not be aware that the code is not of sufficient strength, and the person to whom the key is issued is not able to unlock the lock using that key.
To encode a key with specific magnetic areas in the form of a code to actuate magnetic tumbler pins, the location of the area must be accurately made or the pin may not be moved out of locking position in the lock. A coding fixture such as described in the Sedley '851 patent is normally used into which the key to be encoded is manually placed behind a plate pierced with holes at the exact location where magnetic areas could be applied to the inserted key. The holes are sized to accept the tip of the encoding device which, when energized by the electronic circuit inside the device, creates a strong magnetic field of either North or South polarity which is transferred into the key at the location of the selected hole.
So that a record is made of where to encode the said magnetic areas on a card, a code template is first created which is a paper or plastic sheet on which is printed the pattern of the complete array of magnetic areas that could be encoded on a key for a particular type of magnetic lock or locks. Typically specific holes are punched out of this code template with a hole punch or other tool. In a preferred embodiment of such a code template, there are two identical array fields printed on the card side-by-side. The hole locations are numbered to identify which pin tumbler in the lock would be affected by a magnetic area of the key when said key is inserted into the card lock.
Typically one of the arrays of numbers is for encoding all the North magnetic areas and the other is used for encoding all the South areas. Using two separate areas reduces the potential error if both polarities were punched into one array and the person doing the encoding had to change the polarity while selecting holes in the card to be coded. Also it is easier to miss one or more holes while encoding in this way.
The use of such a card with two arrays of numbers along with a code fixture that has only a single key slot for insertion of the key to be coded, however, requires that the code template card be moved after encoding the first polarity section so that the second array overlays the key to be encoded and then those areas can be encoded on the key.